The present invention relates to an image forming apparatus for forming an image on a paper sheet in a printer unit on the basis of image data acquired by reading an original in a scanner unit.
There is known a conventional image forming apparatus having both a copying function of printing read image data and a scanner function of outputting image data to the outside. In this type of image forming apparatus, a void area (where no printing being effected) is provided on a peripheral portion of a paper sheet at the time of printing. This facilitates separation from a photosensitive drum in a printing process and prevents a stain on a transfer belt due to toner which has not been transferred onto a paper sheet.
In the copying function, when an input operation for an original is performed, only an area which will be actually printed on a paper sheet is read (a portion which will become a void at the time of printing is not read).
Specifically, when a copying operation with a magnification of, e.g. 100% is performed for an original shown in FIG. 11A, an area obtained by excluding a peripheral portion of “void width×100÷a magnification (100)” from an image to be printed on a paper sheet is read, as shown in FIG. 11B. In other words, a control is effected to provide a predetermined void on an image to be printed on the paper sheet, as shown in FIG. 1C. The paper sheet in this context refers to a printing medium.
For example, when the magnification is 50%, an area obtained by excluding a peripheral portion of “void width×100÷a magnification (50)” from an image to be printed on a paper sheet is read, as shown in FIG. 11D. At the time of printing, a void is provided as shown in FIG. 11E.
For example, when the magnification is 400%, an area obtained by excluding a peripheral portion of “void width×100÷a magnification (400)” from an image to be printed on a paper sheet is read, as shown in FIG. 11F. At the time of printing, a void is provided as shown in FIG. 11G.
On the other hand, in the scanner function, enlargement/reduction is performed not only to merely vary the dimensions of an image, but also to realize a resolution conversion means. In this case, too, the read area is determined by the same method as with the above-described copying function.
In the conventional method, however, when the resolution conversion is performed by the scanner function, the read area on the original is varied. Consequently, obtained images will vary depending on the resolution. Thus, there is such a problem that the read area decreases depending on the resolution and image information (image data on the original) will be omitted.